This project is a continuation of a previous program designed to achieve the following ends: (a) to isolate and characterize the abnormal immunoglobulins appearing in the blood and urine of patients wth multiple myeloma, macroglobulinemia, and related lymphomas; (b) to study the chemical, physical, and immunological relationships of these immunoglobulins, particularly of IgM and IgA to each other and to Bence Jones proteins and normal immunoglobulins; (c) to undertake comparative structural study of pathological IgM, IgA, and IgG immunoglobulins and of Bence Jones proteins and normal immunoglobulins; (d) to do complete amino acids sequence analysis of Bence Jones proteins and the light chains of immunoglobulins; (e) to undertake complete amino acid sequence analysis of the heavy chains of IgA and IgG myeloma globulins and of pathological IgM human macroglobulins. The overall purpose is to ascertain the structural relationships among these proteins in relation to the problems of immunoglobulin biosynthesis, evolutionary development, genetic control, and antibody specificity and to develop information, reagents, and procedures of value for study of lymphomas and autoimmune diseases.